JPH06343168A - Encoding method for digital signal, method for generating table for encoding, encoding device and encoding method - Google Patents

Abstract

PURPOSE:To improve encoding efficiency by converting digital signals to data strings, obtaining plural events and setting one code word corresponding to each event one before. CONSTITUTION:Picture data are conversion-processed in a conversion circuit 2, turned into coefficient data and supplied to a quantization circuit 3. The quantization circuit 3 quantizes the coefficient data from the conversion circuit 2 and the quantized coefficient data are supplied to a variable length encoding circuit 4. The plural events composed of continuous 0 coefficients provided with a prescribed run length and at least one non-0 coefficient ranged in front or at the back of the continuous 0 coefficients are obtained from the data strings here. Then, corresponding to each event one before, based on table data for supplying the different code words to the respective events, one code word is set to the plural events. The table data are loaded from a Huffman table generating device to the memory 4a of the variable length encoding circuit 4, for instance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal encoding method, an encoding table generating method, and an encoding method suitable for being applied to an apparatus for transmitting, recording or reproducing various information such as video and audio. The present invention relates to an encoding device and an encoding method.

[0002]

2. Description of the Related Art Conventionally, various video signal coding apparatuses have been proposed in order to transmit or record an image at a bit rate as small as possible while maintaining sufficient quality. As an example thereof, a high efficiency coding device using DCT (Discrete Cosine Transform) and Huffman coding has been proposed. In such an encoding device, data such as video and audio to be encoded is converted into coefficient data from a direct current component to a high order alternating current component for each block by, for example, a discrete cosine transform (DCT) circuit, and the coefficient data is converted. The data is quantized, and the quantized coefficient data is encoded by the variable length coding circuit.

In the DCT, the DC components of the blocked data to the high-order AC components are converted into two-dimensional coefficient data. Then, the transform coefficient obtained by this transform is scanned (zigzag scan) and encoded as shown in FIG. Encoding is performed according to the scanning order, and the coding range extends to the last non-zero coefficient after quantization.

The coefficient data within the coding range by the zigzag scanning is arranged in one column as shown in FIG. 25, for example, and the coefficient data arranged in one column is the Huffman code as described above in the variable length coding circuit. It is encoded by a method such as encoding. This Huffman coding technique is disclosed in Japanese Patent Application Laid-Open No. 63-63
It is disclosed in Japanese Patent Laid-Open No. 132530.

In FIG. 25, DC is coefficient data of a DC component (in this example, it is "168"), AC0
1 to AC33 are AC component coefficient data, and the larger the number attached to the AC component coefficient data, the higher the AC component. As shown in this figure, from the coefficient data DC of the DC component to the coefficient data AC33 of the high-order AC component
Are sequentially coded into codes C1 to Cn. Further, as shown in FIG. 25, when each coefficient data is encoded,
Encoding is performed by using consecutive "0" s and the subsequent values. As a word indicating the number of consecutive "0" s,
The word "0 run" is used. For example, "0 run 0"
When it is described that the number of consecutive “0” s (0 runs) is “0”, that is, there is no “0”.

In FIG. 25, the AC component coefficient AC2
Since 0 is “0”, the following AC11 is “0”, the following AC02 is “0”, and the following AC03 is “4”, this is called “0 run 3 value 4” in this case. Also,
Since the AC component coefficient AC01 is "120", the term "0 run 0 value 120" is used in this case.

Now, a case of encoding the coefficient data shown in FIG. 25 will be described with reference to FIG. FIG. 26
Is a table for giving a code according to the value following 0 run and the last "0". For convenience of explanation, FIG. 26 shows only the value of 0 run shown in FIG. 25 and the coefficient value following it. The table shown in FIG. 26 is created according to a known Huffman code creation procedure.

First, the coefficient AC01 of the AC component is "12".
Since it is "0", it becomes "0 run 0, coefficient value" 120 "" as shown in FIG. 26. Therefore, the variable length code to be assigned is, for example, the code C1, and the AC component coefficient AC10 is "50".
Therefore, as shown in FIG. 26, “0 run 0, coefficient value“ 5
Since it is "0"", the variable length code to be assigned is, for example, the code C2.

The following coefficient AC20 is "0" and coefficient AC11.
Is "0", the coefficient AC02 is "0", the coefficient AC03 is "4", that is, three "0" s are consecutive and the next non-zero "4" is lined up. As shown in 26, “0 run 3, coefficient value“ 4 ”” is set, and therefore, the variable length code to be assigned is the code C3. Similarly, the coefficient AC1
Since 2 is "0", the coefficient AC21 is "0", and the coefficient AC30 is "3", in this case, as shown in FIG.
The run 2 and the coefficient value “3” ”are set, and the variable length code to be assigned is the code C4.

Next, since the coefficient AC31 is "1", in this case "0 run 0, value" 1 "" as shown in FIG. 26, the variable length code to be assigned is code C5. Next, since the coefficient AC22 is “0”, the coefficient AC13 is “0”, and the coefficient AC23 is “1”, in this case, as shown in FIG. 26, “0 run 2, value“ 1 ”” is obtained, and therefore, The code to be assigned is code C6. Since the coefficient AC32 is "1", it is "0 run 0, value" 1 "" as shown in FIG. 26, and therefore the code to be assigned is the code C7. Similarly, the coefficient AC33 is "1", so that it is shown in FIG. Thus, "0 run 0, value" 1 "" is set, and the code to be assigned is code C8.

As described above, in the conventional coding apparatus, the coefficient data obtained by the discrete cosine transform is scanned from the DC component to the high-order AC component by the zigzag scan to determine the coding range of the coefficient data, The coefficient data within the coding range is arranged in one column in the order of zigzag scan scanning, and the coefficient data arranged in one column is created according to the Huffman code creation procedure, that is, the number of consecutive "0" s and Encoding is performed by referring to a table made up of codes corresponding to non-zero values that follow.

The applicant of the present invention first performs transform coding such as cosine transform on a two-dimensional image block consisting of (n × n) pixels, and sets the DC component obtained by transform coding to a predetermined bit. Number, the (n 2 −1) AC component is divided into (m × m) (n> m) sub-blocks, and sub-block address information having significant data is provided in sub-block units. By transmitting significant coefficient data in the sub-block to be transmitted, a data transmission device is proposed in which the amount of transmission data can be controlled to be smaller than a predetermined target value by feed-forward control (Japanese Patent Laid-Open No. HEI 2). -226
886).

Further, the present applicant previously carried out transform coding such as cosine transform on a two-dimensional image block consisting of (n × n) pixels, and the direct current component obtained by the transform coding is subjected to predetermined bits. Number, and detects the frequency of occurrence in a unit period such as 1 field, 1 frame, etc., for (n 2 −1) AC component data, converts the frequency of occurrence to cumulative distribution data, and calculates the cumulative frequency distribution. A data transmission device has been proposed in which the amount of generated data in a unit period is controlled to be smaller than the target amount of transmitted data by referring to the data (see Japanese Patent Laid-Open No. 2-238787).

[0014]

As described above, the DC
In transform coding such as T, a block is zigzag scanned from a low-order coefficient to a high-order coefficient, and a consecutive "0" and a number other than "0" are paired to uniquely determine a code. Was assigned. Even in subband coding,
It is common to assign a code that is uniquely determined to a set of consecutive "0" s in the band or between the bands and the following coefficient.

In these methods, when the compression rate is high, "0" is continuous, and efficient coding is possible, but when the compression rate is low, "0" is reduced, so that the coding is efficient. Can not do it. That is, the above-described transform coding that uniquely assigns a code to coefficient data has a disadvantage that the coding efficiency cannot be improved.

The present invention has been made in order to solve such a point, and an object of the present invention is to propose an encoding device capable of greatly improving the encoding efficiency.

[0017]

According to the method of encoding a digital signal of the present invention, the digital signal is composed of continuous zero coefficients.
Step (a) of converting into a continuous data string with non-zero coefficients
And (b) obtaining from the data sequence a plurality of events consisting of a succession of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the succession of zero coefficients; Step (c) of setting one code word for a plurality of events based on table data that gives different code words for each event according to each event.

The encoding table generating method of the present invention is
A step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous; from the data string, a series of zero coefficients having a predetermined run length and a series of zero coefficients Obtaining a plurality of events with at least one non-zero coefficient preceding or following (b)
And (c) detecting the occurrence frequency of each event that appears after the event for each of the plurality of events, and the desired data string is set to the state of the previous data string according to the occurrence frequency of each event. According to the step (d) of generating table data to be used for encoding and storing the table data in the memory.

The digital signal encoding method of the present invention further comprises a step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are connected.
From the data string, a series of zero coefficients having a predetermined run length, and at least one before or after the series of zero coefficients.
Step (b) of obtaining a plurality of events with one non-zero coefficient
And a step (c) of detecting the occurrence frequency of each event that appears next to each of the plurality of events, and a desired data string according to the occurrence frequency of each event obtained in step (c). In step (d) of generating table data for use in encoding according to the state of the previous data string and storing the table data in the memory, and an arbitrary digital signal with continuous zero coefficient and non-zero coefficient. A step (e) of converting into a continuous data sequence, a step (f) of obtaining each event from the data sequence obtained in the step (e), and a plurality of events obtained in the step (f) based on the table data. On the other hand, the step (g) of determining one codeword.

Further, the encoding device of the present invention comprises conversion means 2 and 3 for converting a digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and continuous zero coefficients having a predetermined run length. , A storage means 4a for storing a plurality of table data representing a code word to be given to the next event with respect to a plurality of events consisting of at least one non-zero coefficient preceding or following the sequence of zero coefficients. And a plurality of events from the data string, and based on the table data, the encoding means 4 gives one code word to each of the plurality of events.

The digital signal encoding method of the present invention further comprises a step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are connected.
Step (b) of classifying the non-zero coefficients into a plurality of groups according to their values, a sequence of zero coefficients having a predetermined run length and at least one sequence preceding or following the sequence of zero coefficients from the data sequence. Step (c) of obtaining a plurality of events consisting of non-zero coefficients, and for each of the events, based on the table data that gives the codeword for each group in the previous event, It comprises a step (d) of determining one codeword each.

Further, in the above-mentioned digital signal encoding method of the present invention, in step (d), the rank information in the group is further added to the code word.

The digital signal encoding method of the present invention further comprises a step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and a predetermined run length from the data string. (B) obtaining a plurality of events consisting of zero coefficients with and at least one non-zero coefficient preceding or following the succession of zero coefficients, and classifying the non-zero coefficients into a plurality of groups according to their values. Step (c), detecting the frequency of occurrence of each event that appears next for each group, and changing the desired data string to the state of the previous data string according to the frequency of occurrence of each event. Step (e) of generating table data to be used according to the corresponding encoding and storing it in a memory, and a step of converting an arbitrary digital signal into a data string in which continuous zero coefficients and non-zero coefficients are connected. (F), a step (g) for obtaining each event from the data string obtained in step (f), and one for each of the plurality of events obtained in step (g) based on the table data. And a step (h) of determining a code word.

Further, the encoding device of the present invention comprises a plurality of converting means 2 and 3 for converting a digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and non-zero coefficients in accordance with the values thereof. For each of a plurality of events consisting of the classifying means 4 for classifying into a group, a series of zero coefficients having a predetermined run length, and at least one non-zero coefficient preceding or following the series of zero coefficients, In response to the plurality of events, the storage means 4a stores a plurality of table data representing a code word to be given to each subsequent event, and a plurality of events are obtained from the data string, and based on the table data, And a coding means 4 for giving one code word each.

Further, the encoding apparatus of the present invention comprises conversion means 2 and 3 for converting a digital signal into a data string of a predetermined form.
A storage unit 4a storing a plurality of table data selected based on the previously encoded data sequence, and a data sequence based on the table data selected according to the previously encoded data sequence. And encoding means 4 for encoding.

[0026]

According to the above-described digital signal encoding method of the present invention, the digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected in step (a), and the data is converted in step (b). From the sequence, obtain a plurality of events consisting of a succession of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the succession of zero coefficients, and in step (c) for each previous event. Accordingly, one code word is set for a plurality of events based on table data that gives different code words for each event.

Further, according to the above-described encoding table generating method of the present invention, in step (a), a predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and step (b) ) From the data string,
Obtaining a plurality of events consisting of a succession of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the succession of zero coefficients, for each of the plurality of events in step (c), A table used for detecting the occurrence frequency of each event that appears after the event and encoding the desired data string according to the occurrence frequency of each event in step (d) according to the state of the previous data string Generate data and store in memory.

According to the digital signal encoding method of the present invention described above, in step (a), the predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected, and step (b) ) From the data sequence, a plurality of events consisting of a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients is obtained, and the plurality of events are obtained in step (c). For each of the above, the occurrence frequency of each event that appears after that event is detected, and the desired data string is changed to the previous data string in accordance with the occurrence frequency of each event obtained in step (c) in step (d). Table data to be used for encoding in accordance with the state of (3) is generated and stored in a memory, and in step (e), an arbitrary digital signal is connected by continuous zero coefficient and non-zero coefficient. Each event is obtained from the data sequence obtained in step (e) in step (f), and converted into a plurality of events obtained in step (f) based on the table data in step (g). On the other hand, one codeword is determined.

Further, according to the above-described configuration of the encoding apparatus of the present invention, the conversion means 2 and 3 convert the digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and a predetermined run length is obtained. Storing a plurality of table data representing a code word to be given to the next event with respect to a plurality of events each of which has a series of zero coefficients and at least one non-zero coefficient that continues before or after the series of zero coefficients Stored in the means 4a, the encoding means 4 obtains a plurality of events from the data sequence,
One code word is given to each of a plurality of events based on the table data.

According to the digital signal encoding method of the present invention described above, in step (a), the predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected, and step (b) ), The non-zero coefficient in
According to the value, it is classified into a plurality of groups, and in the step (c), a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients are connected. Multiple events,
In step (d), one codeword is determined for each of a plurality of events based on the table data that gives a codeword for each group in the preceding event for each event.

Further, according to the digital signal encoding method of the present invention described above, in step (d), the rank information in the group is further added to the code word.

According to the above-described digital signal encoding method of the present invention, in step (a), a predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected, and step (b) ), A plurality of events consisting of a zero coefficient having a predetermined run length and at least one non-zero coefficient preceding or following a series of zero coefficients are obtained from the data sequence, and the non-zero coefficient is obtained in step (c). It classifies into a plurality of groups according to the value, detects the occurrence frequency of each event that appears next to each group in step (d), and determines the desired frequency according to the occurrence frequency of each event in step (e). Table data to be used when the data string of is encoded according to the state of the previous data string is generated and stored in the memory, and in step (f) any digital signal is It is converted into a continuous data string of zero coefficients and non-zero coefficients, each event is obtained from the data string obtained in step (f) in step (g), and based on the table data in step (h), Step (g)
One codeword is determined for each of the plurality of events obtained in step 1.

According to the configuration of the encoding apparatus of the present invention described above, the conversion means 2 and 3 convert the digital signal into a data string in which continuous zero coefficients and non-zero coefficients are connected, and the classification means 4 converts Zero coefficients are classified into a plurality of groups according to their values, and a plurality of events consisting of a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients are provided. On the other hand, according to each group, a plurality of table data representing a code word to be given to the next event is stored in the storage means 4a, the encoding means 4 obtains a plurality of events from the data string, and the table data is obtained. Based on the above, one code word is given to each of a plurality of events.

Further, according to the configuration of the encoding apparatus of the present invention described above, the converting means 2 and 3 convert the digital signal into a data string of a predetermined form, and the data string selected last time is selected. A plurality of table data are stored in the storage unit 4a, and the encoding unit 4 encodes the data string based on the table data selected according to the previously encoded data string.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital signal coding method, a coding table generating method, a coding apparatus and a coding method according to the present invention will be described in detail below with reference to FIGS.

First, a high-efficiency coding apparatus to which the digital signal coding method, coding apparatus, and coding method of the present invention are applied will be described with reference to FIG. FIG. 1A shows an encoder of the high efficiency encoder, and FIG. 1B shows a decoder of the high efficiency encoder.

First, the encoder will be described with reference to FIG. 1A. In FIG. 1A, 1 is, for example, a digital V
An input terminal to which image data or the like to be converted from an electronic device main body circuit such as TR is supplied, and image data is supplied to the conversion circuit 2 via the input terminal 1.

The transform circuit 2 is, for example, a discrete cosine transform (DCT) circuit, which performs the discrete transform process on the image data supplied through the input terminal 1 for each block using only the cosine function, and as described above. First, the coefficient data from the DC component to the high-order AC component is obtained. Examples of orthogonal transforms considered here include Fourier transform, Hadamard transform,
The Karonen-Loeve transform is conceivable, but the Fourier transform includes a complex number operation and has a complicated configuration. Further, as a conversion method other than the orthogonal conversion, for example, slope conversion (slant conversion) or Haar conversion can be considered. In this example,
A high-speed operation algorithm exists, can be realized by a one-chip LSI that enables real-time conversion of images, and uses a DCT that is excellent in power concentration on low-frequency components that directly affect coding efficiency.

The image data is converted by the conversion circuit 2 into coefficient data, which is supplied to the quantization circuit 3. The quantization circuit 3 quantizes the coefficient data from the conversion circuit 2. The quantized coefficient data is supplied to the variable length coding circuit 4. The variable-length coding circuit 4 scans (zigzag scans) the coefficient data from the quantization circuit 3 as described with reference to FIG. Then, the coefficient data within the coding range is arranged in one column as shown in FIG. 4, for example, and the coefficient data arranged in one column is coded by the Huffman coding method.

In this example, when a plurality of tables corresponding to the condition series are prepared in order to code the coefficient data arranged in one column and a certain coefficient data is to be coded, the coefficient before the coefficient data is A table corresponding to the data condition is selected, and the selected table is referred to for encoding. In transform coding, the coefficients after transformation have a correlation with each other, and thus coding can be used to significantly improve coding efficiency.

FIG. 2 is for creating such a table, and is a Huffman table generating apparatus to which the encoding table generating method of the present invention is applied.

In FIG. 2, reference numeral 11 denotes an input terminal to which a video signal having the same content is supplied in a predetermined cycle, for example, and an external video signal is supplied to the conversion circuit 12 via the input terminal 11. The conversion circuit 12 performs conversion processing such as DCT (Discrete Cosine Transform) on the video signal supplied from the outside through the input terminal 11, and supplies the converted video signal to the quantization circuit 13.

The quantization circuit 13 quantizes the transform output from the transform circuit 12, that is, coefficient data, and supplies it to the Huffman coding circuit 14. The Huffman coding circuit 14 performs Huffman coding on the quantized coefficient data from the quantization circuit 13 by referring to the table stored in the memory 16, and supplies the total code length data to the quantization circuit 13. This total code length data is for changing the coarseness of quantization in the quantization circuit 13. Here, although not shown, the memory 16 is a read-out circuit and a write circuit and, for example, a DRAM (dynamic RAM) or an SRAM (static RAM).
And the like memory circuit.

On the other hand, the coefficient data from the quantizing circuit 13 is also supplied to the occurrence frequency detecting circuit 15. The occurrence frequency detection circuit 15 detects the occurrence frequency of the coefficient data from the quantization circuit 13, generates a table for Huffman coding based on the result, and supplies the generated table data to the memory 16.

Next, the operation of the Huffman table generator shown in FIG. 2 will be described. For example, a video signal for creating a table having a predetermined length is repeatedly supplied to the input terminal 11. Further, a table randomly selected as an initial value is loaded in advance from the occurrence frequency detection circuit 15 in the memory 16.

The quantizing circuit 13 quantizes the table forming video signal of a predetermined length from the input terminal 11 with, for example, the roughness by the initial control from the Huffman coding circuit 14, and quantizes the coefficient data to the Huffman coding circuit 14. And to the occurrence frequency detection circuit 15, respectively. The Huffman encoding circuit 14 encodes the coefficient data according to the table loaded as an initial value from the memory 16.

On the other hand, the occurrence frequency detection circuit 15 detects the occurrence frequency of the coefficient data from the quantization circuit 13, creates a new table based on the detection result, and loads the created new table into the memory 16. .

The condition series referred to here is "0 run, value (coefficient value)". In addition, the detection of the occurrence frequency referred to here is to obtain the occurrence probability of a set of 0 runs and values for each condition series. Then, using this occurrence probability, a code set for each condition series is created according to the Huffman method. As is well known as this method, a symbol (a set of 0 run and value)
Are arranged in descending order of occurrence probability, symbols “1” and “0” are arbitrarily assigned to the symbol with the smallest occurrence probability and the symbol with the second smallest occurrence probability, and these two symbols are considered as one symbol and merged. The number of symbols is reduced by 1 by making the occurrence probabilities of the generated symbols the sum of the occurrence probabilities before merging, and this is considered as a new information source, and the symbols are again arranged in descending order of occurrence probability. The process is repeated until the symbol becomes “1”, and when the symbol becomes “1”, “1” and “0” initially assigned to the symbol for each symbol are read in the reverse order, and this is read for that symbol. It is to be a code word.

In general, the absolute values of the coefficients in the DCT block tend to be large when one is large and the other coefficients tend to be small when one is small, and are correlated with each other. In other words, the frequency of appearance of a set of 0 runs and values also changes depending on the condition series, and by using this to allocate a variable length code, the overall code length can be further shortened.

When this new table is loaded into the memory 16, the Huffman encoding circuit 14 refers to the table and encodes the coefficient data from the quantization circuit 13 and the total code length data into the quantization circuit 13. To change the roughness of the quantization in the quantization circuit 13. Then, similarly, encoding is performed on the table creating data of a predetermined length based on the changed table, and the total code length data obtained by this encoding is supplied to the quantizing circuit 13 to determine the coarseness of quantization. , The occurrence frequency is detected, a new table is created, and the new table is used for coding to repeat the above-described operation to create a large number of coding tables corresponding to the above-described conditional sequences.

The created table data is stored in the variable length coding circuit 4 of the encoder of the high efficiency coding device shown in FIG. 1A.
Memory 4a, such as EEPROM, RAM with backup function, PROM, one-time ROM. As a method of storing this, a method for writing table data with a device for writing data in the memory 4a and mounting the memory 4a in which the table data has been written in the variable length coding circuit 4 and the Huffman table generation device shown in FIG. It is possible to employ any of the methods of loading table data from the table data into the memory 4a of the variable length coding circuit 4.

FIG. 3 is a block diagram showing a concrete example of the configuration of the Huffman table generating apparatus shown in FIG. 3, parts corresponding to those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the figure, 17 is a control unit 17a and RO.
The controller 17 is a controller including an M17b, and the ROM 17b of the controller 17 stores the table data as the default value described above. The control unit 17a supplies a switching control signal to the switch 18 when the power is turned on or when a reset switch (not shown) is pressed, and the movable contact 18c of the switch 18 is connected to one of the fixed contacts 1.
8a.

The movable contact 18c of the switch 18 is connected to the input end of the Huffman coding circuit 14, and the other fixed contact 18b of the switch 18 is connected to the output end of the memory 16. Therefore, the movable contact 18 of the switch 18c
When c is connected to one fixed contact 18a, the ROM 17
The table data as a default value stored in b is loaded into the Huffman encoding circuit 14 via the switch 18, and when the movable contact 18c of the switch 18 is connected to the other fixed contact 18b, it is stored in the memory 16. The generated table data is Huffman coding circuit 14
Loaded in.

When the power is turned on or when the power is reset, the movable contact 18c of the switch 18 is connected to one fixed contact 18a by the controller 17a of the controller 17, so that the table data from the ROM 17b is used as the default value. It is supplied to the encoding circuit 14. The Huffman encoding circuit 14 encodes the coefficient data from the quantization circuit 13 by referring to the supplied table, and supplies the total code length data to the quantization circuit 13 to determine the coarseness of quantization in the quantization circuit 13. To change.

When a new table is loaded into the memory 16, the control section 17a causes the movable contact 1 of the switch 18 to move.
Since 8c is connected to the other fixed contact 18b, new table data from the memory 16 is supplied to the Huffman encoding circuit 14. The Huffman encoding circuit 14 refers to the table to encode the coefficient data from the quantization circuit 13 and supplies the total code length data to the quantization circuit 13 to change the coarseness of quantization in the quantization circuit 13. Let
Then, similarly, encoding is performed on the table creating data of a predetermined length based on the changed table, and the total code length data obtained by this encoding is supplied to the quantizing circuit 13 to determine the coarseness of quantization. , The occurrence frequency is detected, a new table is created, and the new table is used for coding to repeat the above-described operation to create a large number of coding tables corresponding to the above-described conditional sequences. The created table data is
It is stored in the writable memory 4a of the variable length coding circuit 4 of the encoder of the high efficiency coding device shown in FIG. 1A.

As a condition that can be considered when creating the table data as described above, a value of 0 run and a non-zero value following it can be considered. As an example, a case will be described in which the coefficient data arranged in one column shown in FIG. 4 is encoded by referring to the table corresponding to the condition series created as described above.

In FIG. 4, DC is coefficient data of a DC component (in the example of this figure, "168"), AC01 to AC01.
C33 is the AC component coefficient data, and the higher the number attached to the AC component coefficient data, the higher the AC component. As shown in this figure, the coefficient data DC of the DC component to the coefficient data AC33 of the high-order AC component are coded in order from code 1 to code n. Further, as shown in FIG. 4, when each coefficient data is encoded, as described above, the coefficient data is encoded in accordance with the continuous "0" and the value following it. Further, as in FIG. 24, the word “0 run” is used as the word indicating the number of consecutive “0s”. For example, when "0 run 0" is described, the number of consecutive "0" s (0 runs) is "0", that is, "0".
Indicates that there is no.

In FIG. 4, the AC component coefficient AC22
Is "0", the following AC13 is "0", and the following AC23 is "1". In this case, therefore, "0 run 2, value 1". Further, the coefficient AC01 of the AC component is "120", and in this case, it is "0 run 0, value 120".

Next, the coefficient data AC10 shown in FIG.
The case of encoding will be described with reference to FIG. FIG. 5 shows a table of "0 run 0, code of value" 120 "" which is a condition sequence of AC10. That is, as shown in FIG. 5, the table assigns a code corresponding to the value of 0 run and the value of coefficient data for each condition series. Here, the difference from the conventional one is that, in this example, when a large number of tables are created in accordance with the Huffman code creation procedure according to the condition series and a certain coefficient data is to be coded, the That is, a corresponding table is selected from many tables based on the condition of the coefficient data, and the coefficient data is encoded by referring to the selected table.

In FIG. 6, a table created based on the condition series described with reference to FIG. 5 is selected by a series of coefficient data before the coefficient data to be coded, and the code is referenced with reference to the selected table. It is explanatory drawing shown based on the example shown in FIG.

As shown in FIGS. 6 and 4, first, the coefficient AC01 having the value "120" is the head of the AC component, so that there is no condition series. Therefore, for the leading coefficient of the AC component, the variable length code 1 is obtained from the table (table shown in FIG. 26) in which codes are given to the current value, that is, the value of 0 run and the value of the coefficient. To do so.

Subsequently, the AC component coefficient AC10 is "50".
However, since the coefficient before this coefficient AC10 is AC01 and its value is “0 run 0, coefficient value“ 120 ””, a table having this as a condition series is selected from a plurality of tables, and The variable length code 2 is given to the value "50" of the coefficient AC10 by referring to the table.

The subsequent coefficient AC20 is "10", but the coefficient before this coefficient AC20 is AC10 and its value is "0 run 0, coefficient value" 50 "". A table to be used as the condition series is selected, and the variable length code 3 is given to the value "10" of the coefficient AC20 by referring to the table.

The subsequent coefficient AC11 is "20", but the coefficient before this coefficient AC11 is AC20, and the value thereof is "0 run 0, value" 10 "". A table as a sequence is selected, and the variable length code 4 is given to the value "20" of the coefficient AC11 by referring to the table.

The following coefficient AC02 is "30", but the coefficient before this coefficient AC02 is AC11 and its value is "0 run 0, value" 20 "". A table as a sequence is selected, and the variable length code 5 is given to the value "30" of the coefficient AC02 by referring to the table.

The subsequent coefficient AC03 is "41", but the coefficient before this coefficient AC03 is AC02, and its value is "0 run 0, value" 30 "". A table as a sequence is selected, and the variable length code 6 is given to the value "41" of the coefficient AC03 by referring to the table.

The following coefficient AC12 is "10", but the coefficient before this coefficient AC12 is AC03, and its value is "0 run 0, value" 41 "". A table as a sequence is selected, and the variable length code 7 is given to the value "10" of the coefficient AC12 by referring to the table.

Next, the coefficient AC21 is "10",
The coefficient before this coefficient AC21 is AC12 and its value is "0 run 0, value" 10 "". Therefore, a table having this as a condition series is selected from a plurality of tables, and the table is referred to. The variable length code 8 is given to the value "10" of the coefficient AC21.

Next, the coefficient AC30 is "3", but the coefficient before this coefficient AC30 is AC21, and the value thereof is "0 run 0, value" 10 "". Is selected as the condition series, and the variable length code 9 is set to the value “3” of the coefficient AC30 by referring to the table.
give.

Next, the coefficient AC31 is "1", but the coefficient before this coefficient AC31 is AC30, and the value thereof is "0 run 0, value" 3 "". Is selected as the condition series, and the variable length code 10 is set to the value “1” of the coefficient AC31 by referring to the table.
give.

Next, the coefficient AC22 is "0", and the subsequent coefficient A is
C13 is "0" and the following coefficient AC23 is "1",
The coefficient before the coefficient AC22 is AC31, and the value thereof is “0 run 0, value“ 1 ””. Therefore, a table having this as a condition series is selected from a plurality of tables, and the table is referred to to select these. Value of coefficient AC22 is "0", coefficient AC
The variable length code 11 is given to the value "0" of 13 and the value "1" of the coefficient AC23.

Next, the coefficient AC32 is "1", but the coefficients before this coefficient AC32 are AC22, AC13, AC.
23, and the value thereof is “0 run 0, value“ 1 ””, a table having this as a condition series is selected from a plurality of tables, and the value of the coefficient AC32 is set to “1” by referring to the table. A variable length code 12 is given.

Next, the coefficient AC33 is "1", but the coefficient before this coefficient AC33 is AC32, and its value is "0 run 0, value" 1 "". Is selected as a condition series, and the variable length code 13 is set to the value “1” of the coefficient AC33 by referring to the table.
give.

Having described the encoder for encoding as described above, the decoder of the high efficiency encoding apparatus will be described next with reference to FIG. 1B.

In FIG. 1B, reference numeral 6 denotes an input terminal to which transmission data (not shown) or transmission data from an output side of electronic equipment (not shown) or reproduction / readout data is supplied, which is encoded from the input terminal 6. The various types of data are supplied to the variable length code decoding circuit 7. The variable length code decoding circuit 7 decodes the variable length code data supplied via the input terminal 6 to obtain quantized coefficient data, and supplies this coefficient data to the quantization decompression circuit 8.

The quantization restoration circuit 8 restores the coefficient data from the variable length code decoding circuit 7, obtains coefficient data before quantization, and supplies this coefficient data to the inverse transform circuit 9. As the inverse transform circuit 9, inverse transform such as discrete cosine transform and Hadamard transform described for the transform circuit 2 is performed, and original data obtained by performing the inverse transform is output through the output terminal 10 to the high efficiency coding device. It is supplied to the reproduction system of electronic equipment equipped with.

When the variable-length code data is decoded by the variable-length code decoding circuit 7, that is, when "0 run, value" is coded as a condition series, for example, the table used for coding is used as it is. , A table for obtaining the original coefficient data from the coded data (corresponding coefficient data to the coded data, respectively, provided that the data indicating which table is referred to for coding is coded at the time of coding. Must be added to the variable length code decoding circuit 7 in advance.

As described above, in this example, the Huffman table generator is used to detect the frequency of occurrence of the coefficient data quantized by the quantization circuit 13 to create a table, and the Huffman coding is performed based on the created table. The circuit 14 encodes data, and the total code length data at that time is supplied to the quantization circuit 13 to control the coarseness of quantization, and the operation is repeated to obtain a large number of tables based on the condition series (0 runs, values). When the created table is loaded into the memory 4a of the variable length coding circuit 4 of the encoder of the high efficiency coding device and the coefficient data is coded by the high efficiency coding device, the coefficient data before the coefficient data Since the table corresponding to the condition series of is selected and the selected table is referred to for encoding, the overall code length can be suppressed to be short.

Note that, in the above example, FIG.
A case has been described in which a plurality of tables based on the condition series generated by the Huffman table generation device shown in FIG. 1 are written or loaded into the memory 4a of the variable length coding circuit 4 of the high efficiency coding device shown in FIG. 2 and the circuits subsequent to the quantization circuit 13 shown in FIGS. 2 and 3, that is, FIG.
In the case of Huffman coding circuit 14, occurrence frequency detection circuit 1
5, memory 16, Huffman coding circuit 1 in the case of FIG.
4, the occurrence frequency detection circuit 15, the memory 16, the controller 17, and the switch 18 may be incorporated in the variable length coding circuit 4. In that case, the memory 4a shown in FIG. 1 can also be used as the memory 16 shown in FIG. 2 or FIG.

Next, a case where a condition series (size) other than the condition series “0 run, value” described above is used will be described with reference to FIGS. 7 to 23. This "size" is the exponent value of the power when the value of the coefficient is expressed by a power of 2, and is used as an index when the coefficient is classified according to the value. However, the 9th power of 2 is 256, but when this is represented by 9 bits, the maximum value is 255. Therefore, when actually classifying by size, the exponent of the power when the value of the coefficient is expressed by the power of 2 + 1
Becomes

FIG. 7 shows an example in which coefficient data is classified according to a concept called this size. As shown in FIG. 7, a coefficient value "0" is a size 0 (0th power) and a coefficient value "-".
1 ”and the coefficient value“ 1 ”are the size 1 (1st power), ...
Coefficient values "-1023 to -512" and coefficient value "5"
12 to 1023 "is a size 10 (10th power), ... Coefficient values" -8191 to -4096 "and" 4096 to
8191 ″ is classified as size 13 (13th power).

Further, regarding the way of arranging the coefficient data in each size, in this figure, for example, the coefficient data having a large value is arranged in order from the left. How to classify,
It is assumed that the Huffman coding circuit 14 shown in FIGS. 2 and 3 has a table as shown in FIG. In addition, sizes 0 to 13 shown in the figure represent exponents of powers, and coefficient data having values within the range are assigned to these sizes. For example, if the value of the coefficient data is "50", the exponent of the power of "50" is "6", that is, "64" in terms of size. Therefore, as shown in FIG. 7, the coefficient data having the value of “50” has the size 6.

In this example, the values of the coefficient data are classified by size, a large number of tables corresponding to the size of the coefficient data are created, and when the coefficient data is encoded, the size of the previous coefficient data is increased. The table corresponding to is selected, and the Huffman code is given to the coefficient data to be encoded by referring to the selected table. In the example described above, “0 run, value” is the condition series, but in this example, the size is the condition series. However, the same is true in that a table corresponding to the condition series of the previous coefficient data is selected and the selected table is referred to for encoding.

The operation of creating a table corresponding to the condition series (size of the previous coefficient data) using the Huffman table creating apparatus shown in FIGS. 2 and 3 will be described with reference to the flowchart of FIG. . For the leading coefficient of the AC component, the size value is obtained using the table for obtaining the size value from the coefficient value described above (see FIG. 7).

First, in step S1, "0" is substituted into the variable J indicating the value of the size of the coefficient immediately before the condition series. Then, the process proceeds to step S2. That is, the occurrence frequency detection circuit 15 shown in FIGS. 2 and 3 sets the variable J to “0”.

In step S2, it is determined whether or not the maximum value of the size of the immediately preceding coefficient in which variable J ≦ conditional series is satisfied. If “YES”, the process proceeds to step S3, and “N
If it is "O", the table creation process is terminated.

In step S3, for the subset whose previous size is J, the occurrence probability of the current size in that subset is calculated. Then, the process proceeds to step S4.

In step S4, the sizes are checked in descending order of occurrence probability. Then, the process proceeds to step S5.

In step S5, the smallest occurrence probability and the next smallest occurrence probability are degenerated and new sizes are assigned, and the occurrence probabilities are summed up. The sign bit "0" is assigned to the smaller one and the sign bit is assigned to the larger one. Add bit "1". Then, the process proceeds to step S6.

In step S6, it is determined whether or not there is only the probability 1. If "YES", the process proceeds to step S7, and if "NO", the process proceeds to step S4 again. Here, "there is only one with probability 1" is a state in which all of them have been reduced to one as a result of repeating the work of reducing the one with the smallest occurrence probability and the next one to one. .

In step S7, the Huffman code is obtained under the condition that the size of the immediately preceding coefficient, which is the condition series, is the variable J. And step S
Go to 8. That is, when degenerate, by reading the allocated "1" and "0" bits in reverse, the Huffman code for each current coefficient size where the conditional sequence is J is obtained.

In step S8, 1 is added to the variable J.
Then, the process proceeds to step S2 again. That is, the code table for the next condition series is obtained.

In the above example, the condition series may be ignored for the coefficient at the beginning of the AC component, and statistics of all data may be taken.

Next, with reference to FIG. 4 again, the encoding in the case where the condition series is the size will be described. In the following description, reference will be made only to the coefficient data shown in FIG.
Reference numerals "1" to "reference numeral 13", arrows associating these with coefficient data, and a frame surrounding the value of each coefficient data are not referred to.

First, the coefficient AC01 which is the head of the AC component
Is "120" and the size is "7" from the table shown in FIG. By the way, as described in the example in which “0 run, value” is used as the condition series described in the embodiment,
It is the beginning of the AC component. Therefore, as shown in FIG. 23, a variable length code is assigned to the leading coefficient by referring to the table of variable length codes assigned according to the current size of the coefficient. As shown in FIG. 23, this table is a table including a current size of a coefficient and a variable-length code assigned according to the size, and is a table for obtaining the variable-length code from the coefficient at the head of the AC component. .

That is, the coefficient A which is the head of this AC component
Since C01 is “120”, the size “7” is given from the table shown in FIG. 7, and since it is the head of the AC component, the size shown in the table shown in FIG. 23 corresponds to the current size “7” of the coefficient. The variable length code “111110” is given. Here, data indicating "120" in the table shown in FIG. 7 is added to this code.

Here, the data indicating what number is 0
We will count from 0th, 1st, 2nd, etc. The bit length of the data indicating the number is represented by the same bit length as the value of the size. For example, in the case of a coefficient corresponding to the size "7", the bit length of the data indicating the number from the size "7" is 7 bits. Here, the fact that the order of counting the coefficients is changed from "0" makes it possible to represent the data indicating the order by the bit length of the numerical value indicated by the size for all the coefficients in the range of the size.

Now, actually explaining the data indicating what number, the size of the value “120” of the coefficient AC01 is “7”, and the 0th of the size “7” is “−127”. 120 "is -127, -126, ...
Since it is counted as −64, 64, 65, ... 120, in this case, the 120th, that is, “11110
Since it is "00", the encoded output of the value "120" of the coefficient AC01 is "1111110 1111000".

Subsequently, the AC component coefficient AC10 is "5".
0 "and the size is" 6 "from the table shown in FIG. 7, but since the size of the coefficient AC01 before this coefficient AC10 is" 7 ", the size of the previous coefficient" 7 "shown in FIG. Table is selected, and the variable length code "01" corresponding to the size "6" of the current coefficient of the table is given.
Here, data indicating "50" in the table shown in FIG. 7 is added to this code. "5
The size of "0" is "6", and the 0th size of "6" is "-63", so "50" is -63, -62, ...
...- 32, 32, 33, ... 63 are counted, so in this case, it is the 50th.

The following coefficient AC20 is "10" and the size is "4" from the table shown in FIG.
Since the size of the coefficient AC10 before 20 is “6”,
The table of the previous coefficient size “6” shown in FIG. 14 is selected, and the variable length code “00” corresponding to the current coefficient size “4” of the table is given. Here, in this code,
Further, in the table shown in FIG. 7, "10" is added with data indicating the order. The size of "10" is "4", and the 0th of the size "4" is "-15".
"10" is -15, -14, ... -8, 8, 9, ...
Since it is counted as 15, it is the 10th in this case.

The following coefficient AC11 is "20", and the size is "5" from the table shown in FIG.
Since the size of the coefficient AC20 before 11 is "4",
The table of the previous coefficient size "4" shown in FIG. 12 is selected, and the variable length code "110" corresponding to the current coefficient size "5" of the table is given. Here, data indicating "20" in the table shown in FIG. 7 is added to this code. "20" has a size of "5", and the 0th of the size "5" is "-31", so "20" is -31, -30, ... -16,
Since it is counted as 16, 17, ... 31, it is the 20th in this case.

The subsequent coefficient AC02 is "30" and the size is "5" from the table shown in FIG.
Since the size of the coefficient AC11 before 02 is "5",
The table of the previous coefficient size "5" shown in FIG. 13 is selected, and the variable length code "10" corresponding to the current coefficient size "5" of the table is given. Here, in this code,
Further, in the table shown in FIG. 7, "30" is added with data indicating what number it is. "30" has a size of "5"
Since the 0th of the size "5" is "-31", "30" is -31, -30, ... -16, 1
Since it will be counted as 6, 17, ..., 31, it will be the 30th in this case.

The following coefficient AC03 is "41", and the size is "6" from the table shown in FIG.
Since the size of the coefficient AC02 before 03 is "5",
The table of the previous coefficient size "5" shown in FIG. 13 is selected, and the variable length code "111110" corresponding to the current coefficient size "6" of the table is given. Here, this code is added to "41" in the table shown in FIG.
Adds data indicating the order. Since "41" has a size of "6" and the 0th size of "6" is "-63", "63" is -63, -62, ...- 3.
Since it is counted as 2, 32, 33, ... 63, it is the 41st in this case.

The following coefficient AC12 is "10" and the size is "4" from the table shown in FIG.
Since the size of the coefficient AC03 before 12 is “6”,
The table of the previous coefficient size “6” shown in FIG. 14 is selected, and the variable length code “00” corresponding to the current coefficient size “4” of the table is given. Here, in this code,
Further, in the table shown in FIG. 7, "10" is added with data indicating what number it is. "10" has a size of "4"
Since the 0th of the size "4" is "-15", "10" is -15, -14, ... -8, 8,
Since it is counted as 9, ... 15, it is the 10th in this case.

Next, the coefficient AC21 is "10" and the size is "4" from the table shown in FIG.
Since the size of the coefficient AC12 before C21 is "4", the table of the previous coefficient size "4" shown in FIG. 12 is selected, and the variable corresponding to the current coefficient size "4" of the table is selected. The long code "10" is given. Here, in addition to this code, in the table shown in FIG. 7, "10" is added to indicate data. In this case as well, it is the tenth, as described above.

Next, the coefficient AC30 is "3" and the size is "2" from the table shown in FIG.
Since the size of the coefficient AC21 before 30 is "4",
The table of the previous coefficient size "4" shown in FIG. 12 is selected, and the variable length code "011" corresponding to the current coefficient size "2" of the table is given. Here, in addition to this code, in the table shown in FIG. 7, data indicating “three” is added. "3" has a size of "2"
And the 0th of the size “2” is “−3”,
Since "3" is counted as -3, -2, 2, 3,
In this case, it is the third.

Next, the coefficient AC31 is "1" and the size is "1" from the table shown in FIG.
Since the size of the coefficient AC30 before 31 is "2",
The table of the previous coefficient size "2" shown in FIG. 10 is selected, and the variable length code "00" corresponding to the current coefficient size "1" of the table is given. Here, in this code,
Further, in the table shown in FIG. 7, data indicating what number "1" is is added. Since "1" has a size of "1" and the 0th size of "1" is "-1",
Since "1" is counted as -1, 1, it is the first in this case.

Next, the coefficient AC22 is "0", and the size is "0" from the table shown in FIG.
Since the size of the coefficient AC31 before 22 is "1",
The table shown in FIG. 9 in which the size of the previous coefficient is "1" is selected, and the variable length code "00" corresponding to the size "0" of the current coefficient of the table is given. Here, in this code,
In this case, data indicating what number "0" is is not added. Since the size "0" has only "0" as a member, it has no meaning in the data itself indicating the order, so it is not added.

Next, the coefficient AC13 is "0" and the size is "0" from the table shown in FIG.
Since the size of the coefficient AC22 before 13 is “0”,
The table shown in FIG. 8 in which the size of the previous coefficient is "0" is selected, and the variable length code "00" corresponding to the size "0" of the current coefficient of the table is given. Also, as in the above description, no data indicating the order of "0" is added to this code.

Next, the coefficient AC23 is "1" and the size is "1" from the table shown in FIG.
Since the size of the coefficient AC13 before “0” is “0”,
A table whose previous coefficient size is "0" is selected and a variable length code "01" corresponding to the current coefficient size "1" of the table is selected. Here, in addition to this code, in the table shown in FIG. 7, data indicating what number "1" is. Since "1" has a size of "1" and the 0th size of "1" is "-1",
Since "1" is counted as -1, 1, it is the first in this case.

Next, the coefficient AC32 is "1" and the size is "1" from the table shown in FIG.
Since the size of the coefficient AC23 before “1” is “1”,
A table having the previous coefficient size of "1" shown in is selected, and the variable length code "01" corresponding to the current coefficient size "1" of the table is given. Here, in addition to this code, in the table shown in FIG. 7, data indicating what number "1" is. The data indicating the number is “1” as described above.

Next, the coefficient AC33 is "1" and the size is "1" from the table shown in FIG.
Since the size of the coefficient AC32 before “1” is “1”,
A table having the previous coefficient size of "1" shown in is selected, and the variable length code "01" corresponding to the current coefficient size "1" of the table is given. Here, in addition to this code, in the table shown in FIG. 7, data indicating what number "1" is. The data indicating the number is “1” as described above.

On the other hand, when the variable-length code data is decoded by the variable-length code decoding circuit 17, that is, the condition series is the size, the table is selected based on the size of the previous coefficient, and the selected table is referred to. When decoding the encoded code data, as already described, since the data indicating the number of the coefficient data value in the table shown in FIG. 7 is added to the code data, the data shown in FIG. The tables shown in FIGS. 8 to 23 may be used as they are, or a large number of these tables may be compressed exclusively for decoding to create new tables, and the created new tables may be used.

By the way, in this encoding method, since the data indicating the order of the coefficient data value in the table shown in FIG. 7 is added to the coded data, the variable length code decoding circuit 17 Can be easily decoded by referring to the data by simply having the tables shown in FIGS. 7 to 23 or these compressed tables, and the value of the coefficient data of each code data is shown in FIG. Even if the code is the same, the coefficient data of the code can be simplified by detecting the data that indicates the order even if the code is the same. Can be obtained.

As described above, in the present example, the generation frequency of the coefficient data quantized by the quantization circuit 13 is detected to create a table whose size is a condition series, and the Huffman coding circuit is created based on the created table. 14, the total code length data at that time is supplied to the quantization circuit 13 to control the coarseness of the quantization, and a large number of tables based on the condition series are created. When the table is loaded into the memory 4a of the variable length coding circuit 4 of the encoder of the high efficiency coding device and the coefficient data is coded by the high efficiency coding device, it corresponds to the size of the coefficient data before the coefficient data. Since the table is selected and the selected table is referred to for encoding, the overall code length can be kept short. Furthermore, in this example, since the data indicating the order of the size of the coefficient data in the size table is added to the encoded coefficient data, the encoded data can be decoded with a simple configuration and processing. can do.

The above embodiment is an example of the present invention.
It goes without saying that various other configurations can be adopted without departing from the scope of the present invention.

[0118]

According to the above-described digital signal encoding method of the present invention, in step (a), the digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected, and step (b) is performed. In step (c), a plurality of events consisting of a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients are obtained from the data sequence in step (c). Since one codeword is set for multiple events based on table data that gives different codewords for each event according to each event, correlation between coefficients can be used. This has the effect of significantly improving the coding efficiency.

According to the encoding table generating method of the present invention described above, in step (a), a predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected, and step (b) ) From the data string,
Obtaining a plurality of events consisting of a succession of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the succession of zero coefficients, for each of the plurality of events in step (c), A table used for detecting the occurrence frequency of each event that appears after the event and encoding the desired data string according to the occurrence frequency of each event in step (d) according to the state of the previous data string Since the data is generated and stored in the memory, it is possible to create table data that uses the correlation between the coefficients, and this makes it possible to perform encoding when the table data created in this way is used for encoding. There is an effect that the conversion efficiency can be significantly improved.

According to the digital signal encoding method of the present invention described above, in step (a), a predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected, and step (b) ) From the data sequence, a plurality of events consisting of a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients is obtained, and the plurality of events are obtained in step (c). For each of the above, the occurrence frequency of each event that appears after that event is detected, and the desired data string is changed to the previous data string in accordance with the occurrence frequency of each event obtained in step (c) in step (d). Table data to be used for encoding in accordance with the state of (3) is generated and stored in a memory, and in step (e), an arbitrary digital signal is connected by continuous zero coefficient and non-zero coefficient. Each event is obtained from the data sequence obtained in step (e) in step (f), and converted into a plurality of events obtained in step (f) based on the table data in step (g). On the other hand, since one codeword is determined, there is an effect that the correlation between the coefficients can be used, which can significantly improve the coding and decoding efficiency.

According to the encoding apparatus of the present invention described above,
The conversion means converts the digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and a series of zero coefficients having a predetermined run length and at least one non-continuous series before or after the series of zero coefficients. With respect to a plurality of events with zero coefficient, a plurality of table data representing a code word to be given to the next respective events are stored in the storage means, and the plurality of events are obtained from the data string by the encoding means, and the table is stored. Since one codeword is given to each of a plurality of events based on the data, there is an effect that the correlation between the coefficients can be used, which can significantly improve the coding efficiency.

According to the above-described digital signal encoding method of the present invention, in step (a), a predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and step (b) ), The non-zero coefficient in
According to the value, it is classified into a plurality of groups, and in the step (c), a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients are connected. Multiple events,
In step (d), one codeword is determined for each of a plurality of events based on the table data that gives the codeword for each group in the preceding event for each event. , The correlation between the coefficients can be used, which has the effect of significantly improving the coding efficiency.

Further, according to the digital signal encoding method of the present invention described above, in step (d), the rank information within the group is further added to the code word. The efficiency can be improved.

According to the above-described digital signal encoding method of the present invention, in step (a), a predetermined digital signal is converted into a data string in which continuous zero coefficients and non-zero coefficients are connected, and step (b) ), A plurality of events consisting of a zero coefficient having a predetermined run length and at least one non-zero coefficient preceding or following a series of zero coefficients are obtained from the data sequence, and the non-zero coefficient is obtained in step (c). It classifies into a plurality of groups according to the value, detects the occurrence frequency of each event that appears next to each group in step (d), and determines the desired frequency according to the occurrence frequency of each event in step (e). Table data to be used when the data string of is encoded according to the state of the previous data string is generated and stored in the memory, and in step (f) any digital signal is It is converted into a continuous data string of zero coefficients and non-zero coefficients, each event is obtained from the data string obtained in step (f) in step (g), and based on the table data in step (h), Step (g)
Since one codeword is determined for each of the plurality of events obtained in step 1, one codeword is determined, so that the correlation between coefficients can be used, which enables encoding and decoding. There is an effect that efficiency can be significantly improved.

According to the coding apparatus of the present invention described above,
The conversion means converts the digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and the classification means classifies the non-zero coefficients into a plurality of groups according to the values, and sets a predetermined run length. Represents a code word to be given to the next event corresponding to each group, for a plurality of events consisting of a series of zero coefficients and at least one non-zero coefficient preceding or following the series of zero coefficients. Since a plurality of table data are stored in the storage means, a plurality of events are obtained from the data string by the encoding means, and one codeword is given to each of the plurality of events based on the table data, The correlation between the coefficients can be used, which has the effect of significantly improving the coding efficiency.

According to the encoding apparatus of the present invention described above,
The conversion means converts the digital signal into a data string of a predetermined form, stores a plurality of table data selected on the basis of the previously encoded data string in the storage means, and the encoding means stores the data string in front of it. Since the encoding is performed based on the table data selected according to the data string encoded in, the correlation of the preceding and following data can be used, and this can significantly improve the encoding efficiency. There is.

[Brief description of drawings]

FIG. 1 is a block diagram of a high-efficiency coding apparatus showing an embodiment of a digital signal coding method, a coding apparatus, and a coding method according to the present invention.

FIG. 2 is a configuration diagram of a Huffman table generation device showing an embodiment of the encoding table generation method of the present invention.

FIG. 3 is a configuration diagram of a Huffman table generation device showing another example of the encoding table generation method of the present invention.

FIG. 4 is an explanatory diagram for explaining determination of a code for coefficient data, which is used for describing an embodiment of a digital signal coding method, a coding apparatus, and a coding method according to the present invention.

FIG. 5 is an explanatory diagram for explaining a table corresponding to a condition series (0 run, value) used for describing an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

FIG. 6 is an explanatory view showing an example of a case where a code is determined based on a value of coefficient data and a condition series, which is used for explaining an embodiment of a digital signal coding method, a coding apparatus and a coding method according to the present invention. is there.

FIG. 7 is an explanatory diagram showing a table for determining the size of coefficient data, which is used for describing an embodiment of the encoding table generating method of the present invention.

FIG. 8 is a flowchart for explaining an operation of creating a table corresponding to a condition series, which is used for describing an embodiment of the encoding table generating method of the present invention.

[Fig. 9] Fig. 9 is an explanatory diagram showing an example of a table corresponding to a size "0" provided for explaining an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

FIG. 10 is an explanatory diagram showing an example of a table corresponding to a size “1” for explaining an embodiment of a digital signal encoding method, an encoding device and an encoding method of the present invention.

FIG. 11 is an explanatory diagram showing an example of a table corresponding to a size “2” for explaining an embodiment of a digital signal encoding method, an encoding device and an encoding method of the present invention.

[Fig. 12] Fig. 12 is an explanatory diagram showing an example of a table corresponding to a size "3" for explaining one embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

FIG. 13 is an explanatory diagram showing an example of a table corresponding to a size “4” for explaining an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

FIG. 14 is an explanatory diagram showing an example of a table corresponding to a size “5” for explaining one embodiment of a digital signal encoding method, an encoding device and an encoding method of the present invention.

FIG. 15 is an explanatory diagram showing an example of a table corresponding to a size “6” for explaining one embodiment of a digital signal encoding method, an encoding device and an encoding method of the present invention.

FIG. 16 is an explanatory diagram showing an example of a table corresponding to a size “7” for explaining an embodiment of a digital signal encoding method, an encoding device and an encoding method of the present invention.

FIG. 17 is an explanatory diagram showing an example of a table corresponding to a size “8” for explaining one embodiment of a digital signal encoding method, an encoding device and an encoding method of the present invention.

[Fig. 18] Fig. 18 is an explanatory diagram showing an example of a table corresponding to a size "9" provided for explaining an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

[Fig. 19] Fig. 19 is an explanatory diagram showing an example of a table corresponding to a size "10" for explaining an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

[Fig. 20] Fig. 20 is an explanatory diagram showing an example of a table corresponding to a size "11" for explaining an embodiment of a digital signal encoding method, an encoding device and an encoding method of the present invention.

[Fig. 21] Fig. 21 is an explanatory diagram showing an example of a table corresponding to a size "12" for explaining an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

[Fig. 22] Fig. 22 is an explanatory diagram showing an example of a table corresponding to a size "13" provided for explaining an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

[Fig. 23] Fig. 23 is an explanatory diagram showing an example of a table for converting a coefficient at the head of an AC component, which is used for describing an embodiment of a digital signal encoding method, an encoding device, and an encoding method of the present invention.

[Fig. 24] Fig. 24 is an explanatory diagram of a discrete cosine transform scanning method used for explaining a conventional encoding device.

[Fig. 25] Fig. 25 is an explanatory diagram for describing a code determination based on the number of consecutive 0s and a coefficient value following the last 0, which is used for describing a conventional encoding device.

[Fig. 26] Fig. 26 is an explanatory diagram for describing encoding of coefficient data, which is used for describing a conventional encoding device.

[Explanation of symbols]

 2, 12 conversion circuit 3, 13 quantization circuit 4 variable length coding circuit 4a, 16 memory 7 variable length code decoding circuit 8 quantization restoration circuit 9 inverse conversion circuit 14 Huffman coding circuit 15 occurrence frequency detection circuit 17 controller 17a Controller 17b ROM 18 switch

Claims (9)

[Claims] 1. A digital signal comprising a series of zero coefficients,
Step (a) of converting into a continuous data string with non-zero coefficients
And (b) obtaining from the data string a plurality of events consisting of a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients. A step (c) of setting one code word for the plurality of events on the basis of table data which gives different code words for each event according to each preceding event. A method for encoding a digital signal. 2. A step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and a series of zero coefficients having a predetermined run length from the data string. (B) obtaining a plurality of events consisting of at least one non-zero coefficient preceding or following the succession of zero coefficients, and for each of the plurality of events, the occurrence of each event that follows that event. Step (c) of detecting the frequency, and generating table data to be used when encoding the desired data string according to the state of the previous data string and storing it in the memory according to the occurrence frequency of each of the above events. And a step (d) for performing the encoding table generation method. 3. A step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and a series of zero coefficients having a predetermined run length from the data string. (B) obtaining a plurality of events consisting of at least one non-zero coefficient preceding or following the succession of zero coefficients, and for each of the plurality of events, the occurrence of each event that follows that event. According to the step (c) of detecting the frequency and the occurrence frequency of each event obtained in the step (c),
A step (d) of generating table data to be used when encoding a desired data string according to the state of the previous data string and storing it in a memory; A step (e) of converting into a data string continuous with zero coefficients, a step (f) of obtaining each event from the data string obtained in the step (e), and a step (f) based on the table data. ), A step (g) of determining one code word for the plurality of events obtained in (1). 4. A digital signal having successive zero coefficients,
A plurality of events including a conversion means for converting into a data string continuous with non-zero coefficients, a series of zero coefficients having a predetermined run length, and at least one non-zero coefficient continuous before or after the series of zero coefficients. On the other hand, a storage means for storing a plurality of table data representing a code word to be given to each next event, and the plurality of events from the data string, and based on the table data An encoding device comprising an encoding means for giving one codeword to each event. 5. A step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous, and the non-zero coefficients are classified into a plurality of groups according to their values. And (b) obtaining from the data string a plurality of events consisting of a series of zero coefficients having a predetermined run length and at least one non-zero coefficient preceding or following the series of zero coefficients ( c) and a step of deciding one codeword for each of the plurality of events based on table data that gives the codeword for each group in the immediately preceding event for each event (d) ). A method for encoding a digital signal, comprising: 6. The method of encoding a digital signal according to claim 5, wherein in the step (d), ranking information within the group is further added to the code word. 7. A step (a) of converting a predetermined digital signal into a data string in which continuous zero coefficients and non-zero coefficients are connected, and a zero coefficient having a predetermined run length from the data string, (B) obtaining a plurality of events consisting of at least one non-zero coefficient preceding or following a series of zero coefficients, and classifying the non-zero coefficients into a plurality of groups according to their values (c) And (d) detecting the occurrence frequency of each event that appears next for each group, and coding the desired data string according to the state of the previous data string according to the occurrence frequency of each event. (E) generating table data used for conversion and storing it in a memory, and (f) converting an arbitrary digital signal into a data string in which continuous zero coefficients and non-zero coefficients are continuous. , A step (g) of obtaining each of the above events from the data string obtained in the above step (f), and one codeword for each of the plurality of events obtained in the above step (g) based on the above table data. And a step (h) for determining. 8. A digital signal having successive zero coefficients,
Conversion means for converting into a data string that is continuous with non-zero coefficients, classification means for classifying the non-zero coefficients into a plurality of groups according to their values, continuation of zero coefficients having a predetermined run length, and zero For a plurality of events consisting of at least one non-zero coefficient preceding or following a series of coefficients, a plurality of table data representing a code word to be given to the next event according to each group is stored. And storage means, and encoding means for obtaining the plurality of events from the data string and giving one codeword to each of the plurality of events based on the table data. Encoding device. 9. A conversion means for converting a digital signal into a data string of a predetermined form, a storage means for storing a plurality of table data selected on the basis of the previously encoded data string, and the data string. And an encoding means for encoding the data based on the table data selected according to the previously encoded data sequence.